1. Field of the Invention
The present invention relates to an embroidery sewing machine which forms, using a sewing needle carrying a needle thread, an embroidery pattern in an embroidery area on a work sheet by displacing the sewing needle and the work sheet relative to each other.
2. Related Art Statement
There is known an embroidery sewing machine which forms an embroidery pattern by utilizing control data stored in a read only memory (ROM) card. The control data include sewing data for sewing the embroidery pattern on a work sheet, and display data for displaying a symbol or icon representing the pattern on a display for selection of the pattern by a user. The ROM card is set in a data-reading device of the sewing machine, so that the display data are used to display the pattern on the display for selection thereof by the user and, upon selection of the pattern, the sewing data are read in by the sewing machine for being used to embroider the pattern into the work sheet.
Japanese Patent Application laid open for public inspection under Publication No. 4(1992)-30892 discloses an embroidery sewing machine which forms, on a work sheet, an embroidery pattern by filling each of a plurality of blocks as divisions of an embroidery area in which the pattern is formed, with stitches formed using a corresponding one of a plurality of different needle threads having different colors. Thus, the sewing machine is capable of producing an embroidery pattern in a variety of color schemes or designs. Since, however, use of an increased number of color-different needle threads leads to lowering work efficiency because of increased work of changing the needle threads, the number of needle threads used is limited to at most five in the conventional sewing machine.
In the case where five color-different needle threads are used in the above-identified embroidery sewing machine, at most six colors, including the color of the work sheet, may be produced in an embroidery pattern. Thus, the sewing machine suffers from insufficient capability of expression of an embroidery pattern. Furthermore, if an embroidery pattern needing seven or more color-different needle threads is formed using only five needle threads only, the thus formed embroidery pattern may be perceived as a different one by the user or others.